Since 1910, the Smithsonian's National Museum of Natural History has inspired curiosity and learning about the natural world and our place in it.

Exhibits

07/20/2015

Continuing a multi-year relationship with George Washington University’s Museum Education Program, the Deep Time exhibit development team enlisted a group of graduate students to conduct a visitor survey to test the effectiveness of two important exhibition elements. We are those students! We’d love to tell you a little about our research and some lessons we learned on the floor of NMNH.

A formative evaluation, such as this one, occurs before or during the project development and focuses on design improvements before an exhibition is built. This is particularly important for the Deep Time Fossil Hall because this exhibit will be on display for decades after it reopens.

These two areas of the exhibition explain big ideas and ask big questions, such as, “Will the past become our future?” and “How has Earth’s temperature changed over the last 56 million years?” The exhibit developer, Siobhan Starrs, asked us to explore what main ideas visitors understood from the panels, and if visitors struggled with any of the concepts or visual elements. With this in mind, our team came up with the following three evaluation questions:

Which ideas and information are the most salient for visitors?

Do the panels communicate the desired content in a way visitors will understand?

Lesson 1: Standing in between a kid and a Triceratops can be a dangerous business.

To answer these questions, we hit the floor, clipboards in hand. We approached visitors who were entering The Last American Dinosaurs exhibition and asked if they’d be willing to look over the new panels and answer a few questions. Standing in a must-see exhibition meant we had to do our best to keep out of the crowd’s way!

Lesson 2: People can get surprisingly giddy about the idea of a cat-sized horse.

Many visitors were extremely willing (some even excited!) to take a few minutes to help us out. How cool is it for your opinion to impact a permanent exhibition at the Smithsonian? Visitors think it is very cool! We learned a lot about which ideas were not clear, and which examples were the most memorable. For example, the evolution of the size of horses over millions of years was a big hit.

Lesson 3: Visitors are the heart of museums and the insight they provided will be invaluable to the exhibit development.

Finally, as emerging museum professionals finishing up graduate school, it was refreshing to reconnect with day-to-day visitors in the museum. As one of our teammates, Laura, expressed, “It was a pleasure to talk with visitors from across the nation and the world, and to gain insights into the diversity of those who come to the Smithsonian.” All of us were honored to facilitate the concerted effort the Smithsonian Institution makes to gather input from visitors in the creation of exhibits.

What’s Next?

On July 22nd, we will present our findings and deliver a report to the exhibition development team. The Museum values the input of visitors and the valuable insights gleaned from the past GWU evaluation projects. The exhibition team will digest the findings and use them to improve the storytelling and design techniques to improve these areas of the exhibition. We look forward to seeing the final designs and exploring the Deep Time exhibition in 2019, this time as NMNH visitors.

Special thanks to Siobhan Starrs, Angela Roberts, and Amy Bolton for their guidance during the formative evaluation process.

07/06/2015

What’s the largest thing you ever made out of papier mâché? A mask? A bowl? How about a life-size Stegosaurus? Photo by Abby Telfer.

Papier mâché brings to mind messy elementary school projects involving newspaper and glue. So you might be surprised to learn that is was the construction material for “Steggy,” the 111-year-old life-size model Stegosaurus that delighted generations of families in our fossil hall. Now that we’ve closed our fossil hall for renovation, the Stegosaurus has moved to a new home at the Paleontological Research Institution’s Museum of the Earth (MoE) in Ithaca, New York. But before we could pack it up and wish it “bon voyage” we had to take it apart, which gave us a chance to learn how it was built.

It’s now 2015, and “Steggy” is traveling again, this time to New York, where its massive bulk, giant plates, intimidating spikes (and tiny head!) can continue to enthrall visitors. But first, we had to get “Steggy” out the door. Stegosaurus was a hefty dinosaur—adults could grow 30 ft. long and weigh 15,000 lbs.—and our model had been on display for so long that it couldn’t fit through newer areas of the building. So to help “Steggy” on its way, we needed to take it apart.

Inside “Steggy”

In the process, we learned a lot about how “Steggy” was made. In 1903 Charles R. Knight prepared a statuette with guidance from curator Frederic Lucas, which served as the model for a full-sized version sculpted in clay. The fabricators then made a mold of this clay model, and prepared the papier mâché cast from the mold. The papier mâché layers are 3/8 of an inch thick in some areas, and much heavier than your standard elementary school project. Our de-installation team soon discovered that there was also quarter-inch-thick wire embedded in the papier mâché that seemed to spiral around the dinosaur's body to provide additional support.

The de-installation team used a borescope to see inside the model and discovered that the Stegosaurus was assembled in three sections: the head and neck, the body, and the tail. These three parts had separate internal armatures mechanically fastened to each other, and a thin paper fill covered the seams. Once they knew how “Steggy” was constructed, the de-install team could reverse those connections. The de-install team carefully cut off the model’s tail, separated its back, and removed the various platform layers that had accumulated over the years. At last, the Stegosaurus was ready to be shipped.

Before cutting into the model Stegosaurus, the team used a borescope to see what was inside. Photo by Donald E. Hurlbert, Smithsonian.

The team created a small window under the tail in order to disconnect all the bolts joining the internal wooden frames, and then finished cutting through the seam between the model’s tail and body. Photo by Donald E. Hurlbert, Smithsonian.

Once they removed the tail, the team sent their smallest member inside the hollow model to remove all the screws from the angle iron attached to the wooden frame. Photo by James Di Loreto, Smithsonian.

It required some contortion to maneuver around the arrangement of wood and metal support braces. Photo by Donald E. Hurlbert, Smithsonian.

Workers in protective masks and suits made an incision across the model’s back with a multi-tool saw. Photo by James Di Loreto, Smithsonian.

“Steggy” got a bit of a trim off the top so it could fit on the freight elevator. The team used a lift to remove the freed back portion and put it on a separate pallet. Photo by James Di Loreto, Smithsonian.

Putting “Steggy” Back Together

The model Stegosaurus arrived at the Museum of the Earth on May 7th, and visitors will be able to see the entire conservation process all summer, in person and via webcam. Conservators have already reassembled “Steggy” using the original internal armatures (with some modifications) for support. Later in the summer they’ll start the cosmetic work, giving “Steggy” a much-needed paint touchup. The Stegosaurus’s arrival is part of a larger exhibit renovation to their Dino Lab: the new space opens this summer. Along with “Steggy,” it will feature a large Jurassic mural, touchable specimens, dinosaur costumes, a reading nook, and more. And so starts a new chapter in the life of the papier mâché dinosaur.

By Juliana Olsson, Exhibits Writer/Editor, National Museum of Natural History

06/30/2015

Iceland. The country’s name might seem to say it all. But in reality, only about 10 percent of this island nation is covered with ice. The other 90 percent encompasses cooled lava flows and cliff-lined fjords, craters and bubbling hot springs, boulder fields and hardy, persistent plant life.

Forged from volcanoes and glaciers, Iceland’s rugged beauty is captivating. Photographer Feodor Pitcairn and geophysicist and poet Ari Trausti Guðmundsson reveal this land of fire and ice in the new exhibition Primordial Landscapes: Iceland Revealed, opening July 2. Primordial Landscapes looks at some of the Earth’s most dramatic geological processes using themes of Fire, Ice, and Transformation.

Iceland is one of the most geologically active places on Earth. Volcanic eruptions and subsurface geothermal activity produce hot springs, geysers, and steam plumes. Arctic ice and snow, rain, and glacial melt combine to form powerful rivers and waterfalls that carve the Earth’s surface. After active lava flows cool, life slowly and persistently begins to take hold. To see the Icelandic landscape is to see many of our planet’s most fundamental processes at work.

This steam plume is found in the highlands of the Torfajökull volcanic system, which contain big, powerful geothermal fields. Geothermal fields are subsurface reservoirs of the Earth’s heat. On the surface, they produce visible hot springs, geysers, and steam plumes. Image by Feo Pitcairn Fine Art.

Photographer Feo Pitcairn first visited Iceland in 2011 and was captivated by its landscapes. On that and on subsequent visits, he captured the 41 images displayed in the exhibition. “With each return to this place at the edge of the Arctic Circle, I became more intimately humbled by nature’s power,” he said. “I have found great inspiration while sojourning with my camera in these wild and varied landscapes.”

A new landscape of lakes, scree (broken rock) slopes, hills, and large boulders is revealed after a glacier retreats. Soon vegetation settles in, and the land is scattered with hardy flowers, grass, moss, and lichen. Glaciers in Iceland—and throughout the Arctic—are vanishing due to a rapidly warming climate. Image by Feo Pitcairn Fine Art.

In addition to the photography, Primordial Landscapes: Iceland Revealed also features poetry by geophysicist and writer Ari Trausti Guðmundsson, translated from the original Icelandic. Excerpts are printed large scale on the exhibition gallery walls, and a soundscape of Guðmundsson reciting his work in Icelandic is paired with English translations projected onto the walls. The exhibit’s soundscape also includes wind, cracking ice, geysers, and other environmental sounds recorded in Iceland. In addition, visitors can get a close-up view of volcanic rock samples and see several examples of Iceland’s extremely hardy plant life from the NMNH Botany Department’s collection.

NMNH lighting specialist Virginia Croskey created an immersive lighting display for the exhibition to allow visitors to experience a taste of the aurora borealis, or northern lights. After failing to catch a glimpse of the northern lights on a trip to Norway, Croskey saw them earlier this year while visiting Iceland.

“I wanted to show the serenity and magic,” she said. “It’s there—and then it’s not—and it’s back, in a different shape—over there.”

The aurora borealis, or “northern lights,” come from the Earth’s magnetic field being continuously hit by electrically charged particles from the Sun. They are transported toward the magnetic poles, where they collide with nitrogen and oxygen molecules in the upper atmosphere. These molecules absorb the energy and then release it as visible light. Image by Feo Pitcairn Fine Art.

Primordial Landscapes: Iceland Revealed parallels the United States’ 2015-2017 chairmanship of the Arctic Council, the governing body responsible for coordinating policy affecting Arctic nations and indigenous peoples living within the Arctic Circle. The Museum will be celebrating the U.S. chairmanship with public programming and research symposia directed by the Smithsonian’s Arctic Studies Center.

By Laura Donnelly-Smith, Exhibits Writer/Editor, National Museum of Natural History

06/12/2015

Two enormous dinosaurs—Triceratops and Tyrannosaurus rex—reign over the exhibition, “The Last American Dinosaurs: Discovering a Lost World.” The show tells the story of non-avian dinosaurs’ final years in western North America through an extraordinary diversity of fossil animals and plants from the Hell Creek Formation in North Dakota, South Dakota and Montana. (Photo by Donald E. Hurlbert / Smithsonian Institution).

Taking children through a museum can create lifelong memories, but sometimes the excitement can be overwhelming! While T. rex is certainly for all ages, here are some tips for children, ages 4-11, to experience the most in our exhibit The Last American Dinosaurs: Discovering a Lost World.

1. Growing Up Triceratops-Exploring Diet and Growth.

The gargantuan fossilized skeleton of the triceratops will always fascinate children, but what can they learn about the life of this extinct creature from its bones? This exhibit explores how what these animals ate and how they grew. Ask kids to look at the teeth of the Triceratops, what kind of food do you think they ate, and how does this compare with a human diet?Examine the baby and adolescent Triceratops skulls and notice how quickly they grow, how quickly do humans grow? How does the Triceratops change as it gets older? How do people change as they get older?

2. Potty Training the T. rex-More than bones can be fossilized.

Put a new spin on an old favorite by exploring other remnants from the T. rex’s life. Looking at eating habits again, ask kids to find two clues that show what the T. rex ate. The T.rex’s teeth may be the obvious clue, but remember that what goes in must come out! A fossil as rare as its creator, see if children can find the fossilized T. rex corprolite (fossilized poop), complete with bone fragments.

Coprolite replica from 3D scanning, Tyrannosaurid dinosaur. Late Cretaceous Period, 66-68 million years ago. Original in the Royal Saskatchewan Museum, Regina, Saskatchewan, Canada.

3. I Spy an Extinct World- We have more in common with the world of Dinosaurs than you think.

A vivid mural covers a wall with images of an ancient world full of unknown (and some familiar) plants, animals, and insects. Engage your young visitors in a rousing game of “I Spy,” and see how many creatures they can find hidden amongst the leaves. How many of those creatures seem familiar today; did you see that dragonfly? Consider the mammals, what’s different about them? See how many organisms they can find! What about this ancient environment looks the same as today? What’s different?

4. How to become a Fossil-How luck, and a dozen other factors, create fossils.

We see fossils all the time in the museum, but where do they come from, and how do they get here after millions of years? Find out while having fun with the revamped version of the Smithsonian original “How to Become a Fossil” arcade game. People of all ages can make choices that will determine their likelihood at becoming a fossil, but ultimately it’s up to luck!

Screenshot of the arcade-style game “How to Become a Fossil,” based on the original 1988 computer interactive program created by Dr. Kay Behrensmeyer, Roger Cutler, and Alan Cutler.

Now that you know how fossils are made, don’t miss the map of North American dinosaur fossil sites behind the FossiLab. Try to locate where the nearest fossil found to where their home lies. You just might have dinosaurs in your own back yard!

5. One thing Paleontologists Never go Without-Exploring Careers in Science.

Once you know where you’re most likely to find a fossil, you’re going to need to learn how scientists work to dig them out and study them. Journey to the Hell Creek Formation in Montana and North Dakota and find out what it’s like for paleontologists to work in the field. For example, why is toilet paper important to paleontologists? Ask your young visitors to search for the answer, in doing so they’ll explore the tools a paleontologist uses and stories of discoveries. They use toilet paper for more than you might think! What other tools do they use? Some of them are in the exhibit cases, but there are also videos of scientists talking about their adventures out in the field.

Important tools for a paleontologist! What do you use in the field? Share in the comments below.

Just because the dinosaurs are extinct doesn’t mean fun has to be! For an even more hands-on experience explore Q?rius for teens and Q?rius Jr. for K-8, interactive learning spaces where visitors can hold specimens in our collections, like fossils!

By Paige Rylander, Public Affairs Intern, National Museum of Natural History, with special thanks to NMNH educator Amy Bolton

03/31/2015

The Museum’s Hall of Human Origins turned five on March 17! The human ancestors depicted in bronze statues throughout the hall were dressed to celebrate, with party hats and balloons. Visitors joined the celebration, wearing birthday buttons highlighting their favorite ancestors and taking selfies with lifelike head reconstructions of ancient humans.

“By asking the question, ‘What does it mean to be human?’ and taking it across the country, we are trying to open an avenue by which people can make contact with science,” said Dr. Rick Potts, a paleoanthropologist and the director of the Human Origins Program.

Each stop on the exhibition tour will include public gatherings featuring conversations with scientists, civic leaders, and faith leaders about the different ways that people, cultures, and faith traditions interpret what being human means.

Dr. Briana Pobiner, a scientist and educator in the Human Origins Program, said that although evolution can be a tough topic for some people to discuss, she’s been thrilled that nearly all her interactions with visitors on the topic have been respectful and productive.

Discoveries and research are constantly improving and deepening our understanding of human evolution. A fossil jaw recently discovered in Ethiopia, for example, is the oldest ever found in the genus Homo—the group that includes modern humans. Scientists dated it at between 2.75 and 2.8 million years old, or about 400,000 years older than any previously discovered fossils.

And a project to map the Neanderthal genome was first reported in May 2010 (just two months after the Hall of Human Origins opened!). Changes like these will eventually affect the content visitors see in the exhibition—via new dates on timelines, for example, or updates to certain panels. For now, an electronic screen in one part of the exhibition provides timely updates of new findings.

Part of the beauty of the exhibition is that it’s arranged by human milestones: things like using tools and fire, living in social groups, and communicating with symbols. Even as new research provides more information about the specifics, the general organization of the hall will stand the test of time—starting with five more birthdays.

02/22/2015

As our Museum writers, scientists, and exhibition developers produce the script for the new Fossil Hall, they’re discovering lots of fascinating stories about how life evolved. We’ll be sharing some of our favorites here.

Passing cargo ships are a common sight at one of the fossil dig sites along the Panama Canal. Photo by Juliana Olsson.

In March 2014, I visited a fossil excavation project along the Panama Canal run by the Smithsonian Tropical Research Institute. We don’t normally search for fossils in the lush tropics, but the current expansion project to widen the channels and build new locks is exposing more rocks. This gives scientists a rare opportunity to find otherwise inaccessible fossils. It was both strange and wonderful to stand on the 100-year-old canal and look at fossils that were far older. Panama’s story is essentially the tale of multiple waves of invasive species. The formation of this narrow strip of land millions of years ago allowed organisms from North and South America to cross into new environments. Today, humans bring animals and plants to Panama from distant ports. Along the banks of the canal, invasive species separated by millions of years meet—elephant grass native to South Asia slowly encroaches on fossils that reveal new information about our planet’s past.

Panama today is an isthmus (or land bridge) connecting North and South America. Image from freeworldmaps.net.

Lay of the Land

Panama’s geology is crucial to this story of species migration. Before it was an isthmus, Panama was a peninsula jutting off of North America. Between 21 and 18 million years ago, the distance between North and South America was about 124 miles (200 km) and covered in deep seas. The sediments along the canal reveal a series of drastic transformations during this time: underneath volcanic basalt, paleontologists have uncovered a shallow marine environment sandwiched between two terrestrial layers. These layers tell scientists that within the span of a few million years this region was first above sea level, then underwater, then above sea level again, and later covered in lava—all due to tectonic activity. Fast-forward to 1914, when the landscape again changed dramatically (this time thanks to humans): where a land bridge once separated two oceans, the United States government divided the continents by completing a series of canal locks connected by an enormous artificial lake.

Past Invasions

Around three million years ago, land animals migrated in earnest across the Isthmus of Panama. Scientists call this the Great American Biotic Interchange (or GABI). Camels, elephant-like gomphotheres, tapirs, deer, foxes, rabbits, bears, peccaries, and cougars moved into South America while large flightless birds, giant ground sloths, capybaras, armadillos, porcupines, and opossums came north. This migration totally changed the face of the fauna on both continents—in fact, many animals that we think of as stereotypically South American (such as llamas) actually have North American origins.

The rocks along the canal are at least 15 million years older than GABI, so scientists expected to find North American animals like horses, camels, bear-dogs, and raccoons. They didn’t expect South American species, but that is what they are now unearthing. Take the 19.3 million year old boa fossil they found. Boas can swim, but crossing a 124-mile (200 km) seaway is an impressive feat. How did it get to Panama? Did it “island-hop,” or raft across on storm-swept debris? Or was there an older, more solid connection between North and South America? Fossils like this one are pushing back the timing of the formation of the isthmus, and making scientists re-evaluate past assumptions about when and how species migrated.

Paleontologists in hard hats and safety vests walk along the banks of the canal, eyes down, scanning the ground for fossils from the Cascadas Formation. Photo by Juliana Olsson.

Present invasions

Understanding how ancient animals fared in new environments is relevant to our world today because so many plants and animals follow on the heels of humans. These species change ecosystems wherever they’re introduced. For example, elephant grass, or canal grass, grows everywhere along the canal. No one seems to know when it was introduced, though canal workers might have planted it to control erosion along the banks of the original canal cuts. Today it has become a pest: elephant grass is the first plant to appear in new clearings, driving out the native pioneer communities. One scientist is actually doing genetic research to determine if all the grass came from a single introduction or represents multiple arrivals. But that’s a story for another day!

Here on the banks of the Panama Canal the present tangles with the past. Elephant grass—a recent invasive—grows so quickly that it covers the fossil dig sites on the banks of the expanded canal. Paleontologists have only a narrow window of time to recover fossils before the plants take over again and cover the past for good.

The far bank of the canal is already overgrown with grasses and shrubs. Photo by Juliana Olsson.

By Juliana Olsson, Exhibits Writer/Editor, National Museum of Natural History

02/11/2015

Love is in the air at the National Museum of Natural History! Our scientists are helping species look for love in this series of “dating profiles” to celebrate Valentine’s Day. Will #NMNHcupid help them find their one and only?

What I'm doing with my life:I’m currently being featured in the orchid exhibition at the Smithsonian’s National Museum of Natural History! Come check it out, I have my very own panel.

The first thing people usually notice about me: my purple fringe.

3 Things I could never do without:water, light, and of course mycorrizal fungi—couldn’t get my nutrients without them! Seriously, we have a pretty co-dependent relationship, me and those Tulasnella fungi.

On a typical Friday, you’ll find me:growing near a stream, meadow, bog, swamp, ditch, or coniferous forest edge. Actually, that’s where I spend all my days…

The most private thing I'm willing to share: some people are put off by my species name, but I’m not crazy! It’s from the ancient Greek psychodes, which means “butterfly-like.” I guess my petals kind of resemble a fluttering butterfly, and I am pretty soulful.

I'm looking for:a pollinator (preferably a hawkmoth), or even a fun guy—sorry, I mean fungi—to hang out with.

By Juliana Olsson, Exhibits Writer/Editor, National Museum of Natural History

01/20/2015

Orchids are starting to bloom in their greenhouses at Smithsonian Gardens.

January is the nation’s capital is dreary, but the Museum will be bursting with color. We’re filling an entire hall with live flowers for our biannual orchid exhibit, Orchids: Interlocking Science and Beauty, by Smithsonian Gardens and the United States Botanic Garden. The show, which runs January 24th through April 26th, examines how new ideas, technologies, and inventions change the way we study, protect, and enjoy orchids. Just consider the greenhouse, which allows us to grow exotic plants even in the dead of winter.

I took a field trip out to Smithsonian Gardens just to see how the orchids were coming along, and got a tour of the greenhouses from Tom Mirenda, Orchid Collection Specialist. It was the perfect way to spend a drizzly, freezing morning. I asked Tom which orchids were his favorites, which turned out to be an impossible question to answer. His favorites are constantly shifting to whichever plant is “behaving” at the moment. The day I went to visit, that was Angraecum sesquipedale, also known as Darwin’s orchid. In 1862, Charles Darwin famously hypothesized that the large, white, star-shaped orchid was pollinated by a moth with a proboscis long enough to reach the nectar at the bottom of the flower’s 10-16 inchlong spur. Twenty-one years after his death, scientists found the moth with the absurdly long proboscis, Xanthopan morganii praedicta.

Angraecum sesquipedale, the Darwin Orchid.

Some of the orchids in the greenhouses were rare species with fascinating back-stories. Others were hybrids familiar to anyone who’s ever bought a corsage. All were lovely, and will give our dinosaurssome competition for this winter’s coolest museum attraction.

These Psychopsis Butterfly ‘Mountain’ orchids look a bit like butterflies.

Vanda Manuvadee ‘Pramate’ tucked among the other orchids.

Oncidium Volcano Hula Halau ‘Volcano Splendor.’

Phragmipedium Schroederae.

Cymbidium Pierette ‘Milk Tea.’

Speaking of “cool,” how do we get the orchids from their greenhouses at Smithsonian Gardens to the Museum in the bitter cold? With a protective layer of shrink wrap, of course! When the orchids are ready to bloom, we put them on rolling carts, wrap each cart in plastic, load them onto heated trucks, and hustle them over to the Museum. Because this exhibition will be open for a few months, we’ll need to repeat the process many times with new flowers as they bloom.

Twin buds, just waiting to bloom.

Images and text by Juliana Olsson, Exhibits Writer/ Editor, National Museum of Natural History

11/21/2014

In July 2013, the exhibits team went to North Dakota’s Hell Creek Formation to collect 66-million-year-old fossils. These fossils will be on display in our new exhibition on the Last American Dinosaurs while our permanent Fossil Hall is under construction. This is the 7th post in a series about our experiences in the field.

We spent so much time last summer digging around the Hell Creek Formation, we thought it deserved its own blog post. In order to know where to find fossils, you need to know where to find the right rock formations, and for that, you need to know a bit of geology.

Formation Basics

Formations are recognizable rock layers or “strata,” and they vary from region to region. All formations have a particular size, appearance, and history. They can range anywhere from 10 to 10,000 feet in thickness, from 3 to 3,000 miles in area, and encompass thousands to millions of years of time. Geologists usually name a formation based on the location where it is best recognized as a distinct set of rock layers—the Hell Creek Formation was described after a rock outcrop along Hell Creek near Jordan, Montana.

Lots and lots of layers with different textures and colors. Photo by Kirk Johnson/ Smithsonian Institution

The Hell Creek Formation is sedimentary—good for us, since we were interested in finding fossils. Because sediments settle differently in different environments, geologists can distinguish between former lakes, streams, ponds, rivers, swamps, reefs, beaches, and sea-floors. Plants and animals that died in the area were sometimes buried in these sediments, and became fossils. The Hell Creek Formation was formed by sediments deposited in rivers, lakes, and floodplains from 68 to 66 million years ago, and preserves plenty of Late Cretaceous plants and animals.

Where to Look

To find the Hell Creek Formation in North Dakota, we searched along the exposed faces of buttes (small hills with steep sides and fairly flat tops that dot the western landscape). Geologic maps told us where geographically we’d find the Hell Creek Formation, but we still had to find sites where it was exposed in accessible outcrops. Time for an analogy:

Think of a stack of pancakes, with two blueberry pancakes on the bottom, four chocolate chip pancakes in the middle, and three buttermilk pancakes on top. Each flavor represents a new formation, and there are a varying number of thinner depositional layers within each formation. The oldest pancakes are on the bottom, while the ones fresh off the griddle are on top. Geology works the same way: newer things sit on top of the old. But it’s not always that simple…

Geologic forces from plate tectonics—such as volcanism and seismic activity—can fold and fracture formations. Imagine sliding your knife beneath your stack of pancakes and lifting upward, just as geologic forces might fold rocks to form a mountain. The stack will bulge up in the middle until eventually it splits, exposing cross-sections of all your different flavor formations. Similarly, if you started pushing up on the outside edges of your pancakes, you’d get a U-shaped stack: the sides will be tilted up, and you could see the exposed stack on the outside edges.

Now imagine that the chocolate chip pancakes in the middle are the Hell Creek Formation (the chocolate chips are fossils, of course), and that’s how paleontologists think about rock layers. Although it’s possible to drill down to find the layers you want to see, it’s much easier to go to the outer edges where tectonics have pushed them to the surface.

Let erosion do the work! We found lots of great plant fossils in the Hell Creek Formation layers on these buttes. Photo by Kirk Johnson/ Smithsonian Institution

Once we identified the Hell Creek Formation and started prospecting, we soon found what we came for—spectacular Late Cretaceous plant fossils and tiny animal bones, scales, and teeth. On November 25th, you’ll be able to see some of these fossils on display in our new exhibition, “The Last American Dinosaurs: Discovering a Lost World.” Our scientists and volunteers are also preparing some of these fossils for our future main Fossil Hall, opening in 2019.

By Juliana Olsson, Exhibits Writer/ Editor, National Museum of Natural History

11/14/2014

In mid-July of 2013, the exhibits team went to North Dakota to collect 66-million-year-old fossils from the Hell Creek Formation. These fossils will go in our new exhibition on the Last American Dinosaurs while our new Fossil Hall is under construction. This is the 6th post in a series about our experiences out in the field.

Scrambling around the rocks in North Dakota, we became familiar with the boundary between the Cretaceous and Paleogene periods of geologic time, which marks the end of the age of dinosaurs, 66 million years ago. You might remember that the Cretaceous/Paleogene (K/Pg) boundary is an important place-marker chosen by scientists, and it has distinctive physical features that can be found in different locations around the world.

Standing on the K/Pg Boundary, we found evidence of the Cretaceous extinction event right at our feet (literally). Photo by Juliana Olsson/ Smithsonian Institution

Boundaries Mark Important Moments in Time

Early geologists understood that rock layers formed in a sequence, with the oldest layers below the youngest ones. This allowed them to tell relative time in any particular place by looking at the order of the rocks. But there was no real way to tell absolute time, making it difficult to know whether one stack of rocks recorded the same sequence of events as another stack exposed hundreds or thousands of miles away. Identifying distinct global events would help geologists compare distant formations.

Fossils helped. Geologists knew that some fossils were found across wide areas, but only in specific layers of rock. This meant that the original organisms were widespread but only lived for a certain period of time. For example, dinosaur fossils are found in Mesozoic rocks but not older or younger layers, and they lived all across the globe. So their fossils could be used to constrain the age of their surrounding rocks. By using hundreds of different species to carefully correlate many rock layers, early geologists developed a remarkably detailed (and surprisingly accurate) time scale.

As a result, some moments in time became more important than others. The moment when dinosaurs became extinct was especially important because it took place everywhere at about the same time—so this event was used to mark the end of not just the Cretaceous Period but the entire Mesozoic Era.

Once radiometric dating was discovered in 1907, geologists could go back to these rocks and figure out exactly how old they were. Now we know that the Cretaceous Period ended when the dinosaurs went extinct, and that this took place 66 million years ago. With improvements in technique, we can now pinpoint this date to within a few tens of thousands of years—not bad for something that happened so long ago.

Geologists still use events to mark boundaries, precisely because they represent moments in time that were important across the world at the time they took place. But scientists now work to know when these events occurred as precisely as possible.

Time and Rock Formations

A formation is a recognizable layer of rock with a specific history and geographic range, typically named after the location where it was first identified. Formations have their own “boundaries,” called contacts, where they contact a younger layer (above) and an older one (below). But these are physical borders, and in fact one formation can change over to another at slightly different times in different places. Because they form under local geological conditions, formations often do not match exactly with geologic time periods (which are based on global events).

And that’s the tricky thing about boundaries and rocks: they are totally different things. The rocks preserve the boundary, but they are not interchangeable. The boundaries between geologic time periods take place at specific, absolute moments in time, and would exist even if we had no rocks to record it (thankfully, that’s not the case with the K/Pg boundary).

The physical signals of a boundary like the K/Pg are found in formations, but which formation depends on where you’re looking. In the Dakotas and Montana, the K/Pg boundary lies at the top of the 300-foot-thick Hell Creek Formation. This formation contains the rock layer that was the land’s surface when the asteroid hit. It also contains fossils that reveal the world of Tyrannosaurus and Triceratops. Come explore their world (and relive our expedition) in “The Last American Dinosaurs” exhibition, opening November 25th.

By Juliana Olsson, Exhibits Writer/Editor, and Matthew Carrano, Curator of Dinosauria, National Museum of Natural History